Unity C# Array - how to clone

Question

Im developing a small app/game in Unity3D.

The problem is: I need to clone an array (call it tempArray) and make some modifications to it. Then i need to change values of the MAIN array to modified tempArray. However, whenever i make changes to cloned array, the same changes are made to the main one.

So i used the following code:

private Cell[,] allCells = new Cell[256, 256]; private Cell[,] cellClone = new Cell[256,256]; //meanwhile initiated to some values// //Here i clone the array. cellClone = (Cell[,])allCells.Clone(); //Here i output the values for an element from both arrays. Debug.Log(cellClone[0, 0].region.name.ToString()); Debug.Log(allCells[0, 0].region.name.ToString()); //Here i want to change "Region" variable of cellClone ONLY. cellClone[0, 0].setRegion(new Region("testregion123", Color.cyan, false)); //Finally, i output the same values again. Only cellClone should change. Debug.Log(cellClone[0, 0].region.name.ToString()); Debug.Log(allCells[0, 0].region.name.ToString());

However, the output shows that allCells[0,0] element was also changed. This means that any operation I do to the cloned array, is executed to the main array.

EDIT:

After alot of playing around I implemented this as a solution. Im posting this in case anybody has a similar problem.

But Im not sure if this is how its supposed to be done so if anybody has any information - Ill be checking this post.

for (int i = 0; i < allCells.GetLength(0); i++) { for (int j = 0; j < allCells.GetLength(1); j++) { //cellClone[i, j] = allCells[i, j].Clone(); //cellClone[i, j] = new Cell((int)allCells[i, j].position.x, (int)allCells[i, j].position.y, allCells[i, j].getRegionName()); cellClone[i, j] = allCells[i, j].clone(); } }

And the clone function:

public Cell clone() { Cell n = new Cell((int)position.x, (int)position.y, regionName); return n; }

have you checked out `Deep Copy or Clone.? here is some example stackoverflow.com/questions/4054075/… — MethodMan
– MethodMan, Commented Nov 20, 2014 at 19:21
I tried the deep copy. However, i dropped it when it asked me to set "UnityEngine.Vector2" as serializable. — Szlosestack
– Szlosestack, Commented Nov 20, 2014 at 19:53

Jon Skeet · Accepted Answer · 2014-11-20 19:21:49Z

However, the output shows that allCells[0,0] element was also changed. This means that any operation I do to the cloned array, is executed to the main array.

Unless Cell is a struct, your setRegion method (which sounds like it should really just be a Region property) isn't changing the contents of the array at all. It's changing the data stored in the object that both arrays contain a reference to.

You're performing a shallow clone of the array, which means the references are being copied - but each Cell object is not being cloned. (We don't even know whether that operation has been implemented within Cell.)

It sounds like you want to perform a deep clone, something like:

for (int i = 0; i < allCells.GetLength(0); i++) { for (int j = 0; j < allCells.GetLength(1); j++) { cellClone[i, j] = allCells[i, j].Clone(); } }

... where you'd need to implement the Clone method yourself. (It may need to clone the region in turn, for example.)

Ambrose · Accepted Answer · 2016-06-21 17:48:40Z

1

Check this out:

Array.Copy

Array.Copy (Array, Array, Int32)

Easier and only 1 line of code;

answered Jun 21, 2016 at 17:48

Ambrose

536 bronze badges

1 Comment

Ugo Hed Over a year ago

This is the best answer, I don't see why Jon Skeet answer is on top

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